Method and circuit for providing auxiliary power and storage device including the same

ABSTRACT

A method of providing an auxiliary power by an auxiliary power supply. The method may include converting an external power to a plurality of charging voltages; charging a charging circuit with a first charging voltage of the plurality of charging voltages; monitoring a voltage of the charging circuit; when capacitance of the charging circuit is less than a first reference capacitance, charging the charging circuit with a second charging voltage of the plurality of charging voltages, the second charging voltage being higher than the first charging voltage by a first voltage amount; and providing an auxiliary power to outside the auxiliary power supply. The auxiliary power may be generated based on the voltage of the charging circuit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2019-0083951, filed on Jul. 11, 2019, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND

The inventive concept relates to an auxiliary power supply, and moreparticularly, to a method of providing an auxiliary power of anauxiliary power supply that secondarily supplies power, an auxiliarypower supply circuit, and a storage device including the same.

Memory systems including memory devices and a memory controller areusually supplied with an external power when operating the memorysystems. Sudden power off (SPO) may occur such that power is abruptlycut off during the operation of memory systems. At this time, since thememory controller stores data using volatile memory, the data stored inthe memory may be lost or an operation (e.g., an erase operation or awrite operation) performed by a memory device may not be completed.Therefore, memory systems complete an operation using an auxiliary powersupply and then back data up.

SUMMARY

The inventive concept provides a method of providing an auxiliary powerby an auxiliary power supply, an auxiliary power monitoring circuit, anda storage device including the same.

According to an aspect of the inventive concept, there is provided amethod of providing an auxiliary power by an auxiliary power supply. Themethod includes converting an external power to a plurality of chargingvoltages; charging a charging circuit with a first charging voltage ofthe plurality of charging voltages; monitoring a voltage of the chargingcircuit; when capacitance of the charging circuit is less than a firstreference capacitance, charging the charging circuit with a secondcharging voltage of the plurality of charging voltages, the secondcharging voltage being higher than the first charging voltage by a firstvoltage amount; and providing an auxiliary power to outside theauxiliary power supply. The auxiliary power is generated based on thevoltage of the charging circuit.

According to another aspect of the inventive concept, there is providedan auxiliary power supply circuit. The auxiliary power supply circuitincludes an auxiliary power monitoring circuit configured to provide anauxiliary power to outside the auxiliary power monitoring circuit, and acharging circuit connected to the auxiliary power monitoring circuit.The auxiliary power monitoring circuit includes a converter configuredto convert an external power to a charging voltage and to provide thecharging voltage to the charging circuit, and a voltage monitoringcircuit configured to control the converter based on capacitance of thecharging circuit. The voltage monitoring circuit controls the converterto provide a first charging voltage to the charging circuit when thecapacitance of the charging circuit is equal to or greater than a firstreference capacitance and to control the converter to provide a secondcharging voltage higher than the first charging voltage to the chargingcircuit when the capacitance of the charging circuit is less than thefirst reference capacitance.

According to a further aspect of the inventive concept, there isprovided a storage device including an auxiliary power supply includinga charging circuit and configured to receive an external power and togenerate a main power and an auxiliary power based on the externalpower, and a main system configured to control an operation of theauxiliary power supply. The auxiliary power supply may charge thecharging circuit with a first charging voltage, and when capacitance ofthe charging circuit is less than a first reference capacitance, theauxiliary power supply may charge the charging circuit with a secondcharging voltage higher level than the first charging voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the inventive concept will be more clearly understoodfrom the following detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a block diagram of an electronic device according to anexample embodiment;

FIG. 2 is a flowchart of the monitoring operation of an auxiliary powersupply of an electronic device, according to an example embodiment;

FIG. 3 is a block diagram of an auxiliary power supply of an electronicdevice, according to an example embodiment;

FIG. 4 is a block diagram of a main system of an electronic device,according to an example embodiment;

FIG. 5 is a flowchart of the monitoring operation of an auxiliary powersupply of an electronic device, according to an example embodiment;

FIG. 6 is a graph showing a change in the voltage of a charging circuitover time;

FIG. 7 is a diagram for explaining charging voltage information storedin an auxiliary power supply, according to an example embodiment;

FIG. 8 is a flowchart of the monitoring operation of an auxiliary powersupply of an electronic device, according to an example embodiment;

FIG. 9 is a diagram for explaining charging voltage information storedin an auxiliary power supply, according to an example embodiment;

FIG. 10 is a block diagram of an electronic device according to anexample embodiment;

FIGS. 11A and 11B are block diagrams of auxiliary power supplies of anelectronic device, according to example embodiments; and

FIG. 12 is a block diagram of an example of applying an electronicdevice to a solid state drive (SSD), according to an example embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments will be described in detail with reference to the attacheddrawings. In the drawings, like reference numerals denote like elements,and redundant descriptions thereof will be omitted.

FIG. 1 is a block diagram of an electronic device 10 according to anexample embodiment.

Referring to FIG. 1, the electronic device 10 may include an auxiliarypower supply (or, an auxiliary power supply circuit) 100 and a mainsystem 200. The auxiliary power supply 100 may supply an auxiliary powerto the main system 200, and the main system 200 may perform an operationusing the auxiliary power.

In an example embodiment, the electronic device 10 may include a storagedevice. For example, the electronic device 10 may include a solid statedrive (SSD). When the electronic device 10 includes an SSD, theelectronic device 10 may include a plurality of flash memory chips(e.g., NAND memory chips) storing data.

The electronic device 10 may include a flash memory device including atleast one flash memory chip. In an example embodiment, the electronicdevice 10 may include an embedded multi-media card (eMMC) or an embeddeduniversal flash storage (UFS) memory device. In an example embodiment,the electronic device 10 may include a UFS memory card, a compact flash(CF) card, a secure digital (SD) card, a micro-SD card, a mini-SD card,an extreme digital (xD) card, or a memory stick. However, the electronicdevice 10 is not limited to a memory system.

The auxiliary power supply 100 may perform an operation of repeatedlycharging electric energy using an external power (or, an externalvoltage) supplied through a first power line PL1 and an operation ofsupplying the auxiliary power to a second power line PL2 based on thecharged electric energy. A system including the main system 200 mayoperate using the power supplied through the second power line PL2.

The auxiliary power supply 100 may include an auxiliary power monitoringcircuit 110 and a charging circuit 120. The auxiliary power monitoringcircuit 110 may store electric energy in the charging circuit 120 usingexternal power and monitor the charging circuit 120. In an exampleembodiment, the charging circuit 120 may include at least one capacitor.

The auxiliary power monitoring circuit 110 may charge electric energy inthe charging circuit 120 (e.g., may cause electric energy to be storedby the charging circuit 120) using the external power while the externalpower is being normally supplied to the auxiliary power supply 100. Theauxiliary power monitoring circuit 110 may enable the external power tobe output to the second power line PL2 as a main power (or, a mainvoltage) and block an auxiliary power (or, an auxiliary voltage) chargedin the charging circuit 120 from being output to the second power linePL2.

When external power is not normally supplied to the auxiliary powersupply 100, the auxiliary power monitoring circuit 110 may block themain power from being output to the second power line PL2 and enable theauxiliary power in the charging circuit 120 to be output to the secondpower line PL2. For example, when sudden power off (SPO) occurs andpower is abruptly cut off during the operation of the electronic device10, external power may not be normally supplied to the auxiliary powersupply 100 through the first power line PL1. For example, SPO may occurwhen the voltage level of the main power is lower than an initially-setminimum operation enabling voltage level.

The auxiliary power monitoring circuit 110 may monitor the chargingcircuit 120. For example, the auxiliary power monitoring circuit 110 maymonitor the voltage of the charging circuit 120. In an exampleembodiment, the auxiliary power monitoring circuit 110 may measure avoltage VNd of the charging circuit 120 and monitor a change incapacitance using the measured voltage.

The auxiliary power monitoring circuit 110 may control a chargingvoltage V_C of the charging circuit 120 according to the change incapacitance of the charging circuit 120. The auxiliary power monitoringcircuit 110 may control the level of the charging voltage V_C toincrease when the capacitance of the charging circuit 120 decreases. Forexample, the auxiliary power monitoring circuit 110 may primarily chargethe charging circuit 120 with a first charging voltage V_C1 and, whenthe capacitance of the charging circuit 120 decreases, may charge thecharging circuit 120 with a second charging voltage V_C2. At this time,the level of the second charging voltage V_C2 may be higher than thelevel of the first charging voltage V_C1. Levels of the first and secondcharging voltages V_C1 and V_C2 may be predetermined.

In an example embodiment, charging voltage information IVC, i.e.,information about the charging voltage V_C with respect to the change incapacitance of the charging circuit 120, may be stored in the auxiliarypower monitoring circuit 110. The auxiliary power monitoring circuit 110may control the charging voltage V_C, which is provided to the chargingcircuit 120, based on the charging voltage information IVC. However,embodiments are not limited thereto. The charging voltage informationIVC may be stored in a controller included in the main system 200, andthe auxiliary power monitoring circuit 110 may control the chargingvoltage V_C, which is provided to the charging circuit 120, in responseto a control signal (e.g., a charging voltage change command) from thecontroller of the main system 200.

The main system 200 may operate using power supplied through the secondpower line PL2. For example, when external power is normally supplied tothe first power line PL1, the main system 200 may be supplied with theexternal power as the main power through the second power line PL2.Contrarily, when the external power is not normally supplied to thefirst power line PL1, the main system 200 may be supplied with theauxiliary power through the second power line PL2.

The main system 200 may include hardware or software, each forcontrolling the auxiliary power supply 100. An example of theconfiguration of the main system 200 will be described below withreference to FIG. 4.

As the capacitance of the charging circuit 120 decreases, electricenergy stored in the charging circuit 120 may also decrease according toEquation 1:

E=½CV ²  [Equation 1]

where E is electric energy stored in the charging circuit 120, C isequivalent capacitance of the charging circuit 120, and V is thecharging voltage V_C of the charging circuit 120. Hereinafter, thecapacitance of the charging circuit 120 may refer to the equivalentcapacitance of the charging circuit 120. Accordingly, the auxiliarypower supply 100 may prevent electric energy stored in the chargingcircuit 120 from decreasing by increasing the charging voltage V_C ofthe charging circuit 120 when the capacitance of the charging circuit120 decreases.

FIG. 2 is a flowchart of the monitoring operation of the auxiliary powersupply 100 of the electronic device 10, according to an exampleembodiment.

In an example embodiment, the monitoring operation of FIG. 2 may beperformed on the charging circuit 120 by the auxiliary power supply 100when the external power is normally supplied to the electronic device 10through the first power line PL1.

Referring to FIG. 2, the auxiliary power supply 100 may charge thecharging circuit 120 with the first charging voltage V_C1 in operationS10. The voltage VNd of the charging circuit 120 may gradually increaseand reach the first charging voltage V_C1.

The auxiliary power supply 100 may determine whether capacitance of thecharging circuit 120 is less than a first reference capacitance inoperation S20. In an example embodiment, the auxiliary power monitoringcircuit 110 may measure a discharge time, during which the voltage VNdof the charging circuit 120 decreases while the charging circuit 120 isbeing discharged, and compare the discharge time with a first referencetime, thereby determining whether the capacitance of the chargingcircuit 120 is less than the first reference capacitance. In an exampleembodiment, when the auxiliary power supply 100 receives a controlsignal (e.g., a charging voltage change command CMD_VC in FIG. 9) from acontroller of the main system 200, the auxiliary power supply 100 maydetermine that the capacitance of the charging circuit 120 is less thanthe first reference capacitance.

When it is determined that the capacitance of the charging circuit 120is equal to or greater than the first reference capacitance, theauxiliary power supply 100 may newly perform operation S10. Theauxiliary power supply 100 may newly charge the charging circuit 120with the first charging voltage V_C1.

Otherwise, when it is determined that the capacitance of the chargingcircuit 120 is less than the first reference capacitance, the auxiliarypower supply 100 may charge the charging circuit 120 with the secondcharging voltage V_C2 in operation S30. The voltage VNd of the chargingcircuit 120 may gradually increase and reach the second charging voltageV_C2. At this time, the level of the second charging voltage V_C2 may behigher than the level of the first charging voltage V_C1.

Although it has been described that the auxiliary power supply 100charges the charging circuit 120 with the first charging voltage V_C1 orthe second charging voltage V_C2, embodiments are not limited thereto.An operation of charging the charging circuit 120 with a third chargingvoltage, of which the level is higher than the level of the secondcharging voltage V_C2, may be additionally performed.

In an example embodiment, after operation S30, the auxiliary powersupply 100 may determine whether the capacitance of the charging circuit120 is less than a second reference capacitance. In an exampleembodiment, the auxiliary power monitoring circuit 110 may measure adischarge time, during which the voltage VNd of the charging circuit 120decreases while the charging circuit 120 is being discharged, andcompare the discharge time with a second reference time, therebydetermining whether the capacitance of the charging circuit 120 is lessthan the second reference capacitance. In an example embodiment, whenthe auxiliary power supply 100 receives a control signal from acontroller of the main system 200, the auxiliary power supply 100 maydetermine that the capacitance of the charging circuit 120 is less thanthe second reference capacitance. At this time, the second referencecapacitance may be less than the first reference capacitance.

When it is determined that the capacitance of the charging circuit 120is less than the second reference capacitance, the auxiliary powersupply 100 may charge the charging circuit 120 with the third chargingvoltage. At this time, the level of the third charging voltage may behigher than the level of the second charging voltage V_C2.

FIG. 3 is a block diagram of the auxiliary power supply 100 of theelectronic device 10, according to an example embodiment.

Referring to FIG. 3, the auxiliary power supply 100 may include theauxiliary power monitoring circuit 110 and the charging circuit 120. Theauxiliary power supply 100 may supply the main power or the auxiliarypower to the main system 200.

In an example embodiment, the charging circuit 120 may include at leastone capacitor. Although only one capacitor is illustrated in FIG. 3,embodiments are not limited thereto. For convenience of description, asingle capacitor having an equivalent capacitance C is illustrated as anexample. The charging circuit 120 may be charged with the chargingvoltage V_C provided through a first direct current (DC)-DC converter113.

The auxiliary power monitoring circuit 110 may include a voltagemonitoring circuit 111, the first DC-DC converter 113, a second DC-DCconverter 115, a first switching circuit 117, and a second switchingcircuit 119. The auxiliary power monitoring circuit 110 may monitor achange in the voltage VNd of the charging circuit 120.

The voltage monitoring circuit 111 may monitor the voltage VNd of thecharging circuit 120, i.e., a node voltage of a node Nd connected to thecharging circuit 120. The voltage monitoring circuit 111 may control thefirst DC-DC converter 113 such that the charging voltage V_C output fromthe first DC-DC converter 113 is changed according to the voltage VNd ofthe charging circuit 120. In an example embodiment, the voltagemonitoring circuit 111 may include a micro controller unit (MCU).

In an example embodiment, the charging voltage information IVC, i.e.,information about the charging voltage V_C with respect to the change inthe capacitance C of the charging circuit 120, may be stored in thevoltage monitoring circuit 111. The voltage monitoring circuit 111 maycontrol the first DC-DC converter 113 based on the charging voltageinformation IVC such that the charging voltage V_C corresponding to thecapacitance C of the charging circuit 120 is provided to the chargingcircuit 120.

The first DC-DC converter 113 may convert external power to the chargingvoltage V_C and provide the charging voltage V_C to the charging circuit120. When the first DC-DC converter 113 is used, the amount of electricenergy charged in the charging circuit 120 may increase. In an exampleembodiment, the first DC-DC converter 113 may include a boost converter.

The first DC-DC converter 113 may convert external power to the firstcharging voltage V_C1 and provide the first charging voltage V_C1 to thecharging circuit 120. When the capacitance C of the charging circuit 120is less than the first reference capacitance, the first DC-DC converter113 may provide the second charging voltage V_C2, of which the level ishigher than the level of the first charging voltage V_C1, to thecharging circuit 120. In an example embodiment, when the capacitance Cof the charging circuit 120 is less than the second referencecapacitance, the first DC-DC converter 113 may provide a third chargingvoltage, of which the level is higher than the level of the secondcharging voltage V_C2, to the charging circuit 120.

The second DC-DC converter 115 may be connected between the chargingcircuit 120 and the second switching circuit 119. The second DC-DCconverter 115 may change the level of the voltage VNd provided by thecharging circuit 120. For example, the second DC-DC converter 115 mayconvert the voltage VNd into an auxiliary voltage, which is suitable toa main system (e.g., the main system 200 in FIG. 1), and output theauxiliary voltage to the second switching circuit 119. In an exampleembodiment, the second DC-DC converter 115 may include a buck converter.

The first switching circuit 117 may transmit external power, which issupplied through the first power line PL1, to the main system 200through the second power line PL2. While the external power is beingnormally supplied to the auxiliary power supply 100, the first switchingcircuit 117 may be turned on such that the external power is output tothe second power line PL2 as the main power. When the external power isnot normally supplied to the auxiliary power supply 100, the firstswitching circuit 117 may be turned off and the external power may beblocked from being output to the second power line PL2.

The second switching circuit 119 may transmit the auxiliary voltage fromthe second DC-DC converter 115 to the main system 200 through the secondpower line PL2. While external power is being normally supplied to theauxiliary power supply 100, the second switching circuit 119 may beturned off (e.g., in an open state) and the auxiliary voltage may beblocked from being output to the second power line PL2. When theexternal power is not normally supplied to the auxiliary power supply100, the second switching circuit 119 may be turned on (e.g., in aclosed state) and the auxiliary voltage may be output to the secondpower line PL2.

In an example embodiment, the auxiliary power monitoring circuit 110 maybe implemented by a single chip. For example, the auxiliary powermonitoring circuit 110 may form a power loss protection (PLP) integratedcircuit (IC). In an example embodiment, the charging circuit 120 may beincluded in or separated from the PLP IC.

FIG. 4 is a block diagram of the main system 200 of the electronicdevice 10, according to an example embodiment.

Referring to FIG. 4, the main system 200 may include a power managementcircuit 210, a controller 220, a first memory 230, and a second memory240. In an example embodiment, the power management circuit 210 mayinclude a power management IC (PMIC).

The power management circuit 210 may receive the main power or theauxiliary power from the second power line PL2, may generate outputvoltages respectively suitable to the operations of the controller 220,the first memory 230, and the second memory 240, and may respectivelyprovide the output voltages to the controller 220, the first memory 230,and the second memory 240.

The controller 220 may control the operation, e.g., data read, datawrite, or data erase, of the first memory 230 and the second memory 240.The controller 220 may also control the operation of an auxiliary powersupply circuit (e.g., the auxiliary power supply 100 in FIG. 1). In anexample embodiment, the controller 220 may receive information aboutcapacitance of a charging circuit (e.g., the charging circuit 120 inFIG. 1) and, when the capacitance of the charging circuit 120 is lessthan a first reference capacitance, may control the auxiliary powersupply circuit to increase a charging voltage supplied to the chargingcircuit 120.

In an example embodiment, the controller 220 may include a processor anda working memory and may control the auxiliary power supply 100 througha firmware operation. However, embodiments are not limited thereto, andthe controller 220 may control the auxiliary power supply 100 through ahardware or software operation.

In an example embodiment, the first memory 230 may be a different typefrom the second memory 240. For example, the first memory 230 may be avolatile memory and the second memory 240 may be a non-volatile memory.

For example, the first memory 230 may be implemented as static randomaccess memory (SRAM), dynamic RAM (DRAM), etc. The second memory 240 maybe implemented as flash memory, phase-change RAM (PRAM), ferroelectricRAM (FRAM), magnetic RAM (MRAM), etc.

In an example embodiment, one of the first memory 230 and the secondmemory 240 may be a cache memory and the other may be a main memory.According to the type of main memory, an electronic device (e.g., theelectronic device 10 of FIG. 1) may be an SSD. For example, in the caseof an SSD, DRAM may be used as a cache memory and NAND flash memory maybe used as a main memory. However, embodiments are not limited to thecase where the electronic device 10 is an SSD.

FIG. 5 is a flowchart of the monitoring operation of the auxiliary powersupply 100 of the electronic device 10, according to an exampleembodiment. FIG. 6 is a graph showing a change in the voltage of acharging circuit over time and is provided to explain the operation ofthe auxiliary power supply 100. Redundant descriptions of like numeralsin FIGS. 2 and 5 will be omitted. In an example embodiment, themonitoring operation of FIG. 5 may be performed on the charging circuit120 by the auxiliary power supply 100 when the external power isnormally supplied to the electronic device 10.

Referring to FIGS. 1, 5, and 6, operation S20 may include operation S21and operation S23. The auxiliary power supply 100 may measure adischarge time, which is taken for the charging circuit 120 to bedischarged from the first charging voltage V_C1 to a first thresholdvoltage V_TH1, in operation S20. For example, a level of the firstthreshold voltage V_TH1 may be lower than the level of the firstcharging voltage V_C1 by a first discharge voltage amount DV1.

The auxiliary power supply 100 may determine whether the discharge timeis less than a first reference time interval TR1 in operation S23. Thesmaller the capacitance of the charging circuit 120, the faster theelectric energy stored in the charging circuit 120 may be discharged.For example, when the discharge time taken for the charging circuit 120to be discharged from the first charging voltage V_C1 to the firstthreshold voltage V_TH1 decreases, the capacitance of the chargingcircuit 120 may also be lower. Accordingly, when the discharge time ofthe charging circuit 120 is measured and compared with a reference time,whether the capacitance of the charging circuit 120 is less than thefirst reference capacitance may be determined.

When the discharge time is equal to or longer than the first referencetime interval TR1, the auxiliary power supply 100 may newly performoperation S10.

When a first discharge time, e.g., TD1, is shorter than the firstreference time interval TR1, the auxiliary power supply 100 may performoperation S30. Operation S30 may include operations S31, S33, and S35.

The auxiliary power supply 100 may determine whether the first chargingvoltage V_C1 is a maximum charging voltage in operation S31. The levelof the charging voltage V_C of the charging circuit 120 may be preset,and the maximum charging voltage may be the maximum value of thecharging voltage V_C that guarantees the normal operation of thecharging circuit 120. When the charging circuit 120 is charged with avoltage that is higher than an upper limit voltage V_L, the chargingcircuit 120 may be degraded and may thus not normally operate, and thelevel of the maximum charging voltage may be equal to or lower than thelevel of the upper limit voltage V_L.

When the first charging voltage V_C1 is the maximum charging voltage,the auxiliary power supply 100 may determine the charging circuit 120 tobe a failure in operation S33. The auxiliary power supply 100 may informoutside the electronic device 10, for example, a host, of the failure ofthe charging circuit 120. The electronic device 10 may not use theauxiliary power supply 100 based on information of failure. When thefirst charging voltage V_C1 is the maximum charging voltage, it isdifficult to guarantee the normal operation of the charging circuit 120even if the charging circuit 120 is charged with a voltage that ishigher than the first charging voltage V_C1, and therefore, the chargingcircuit 120 may be determined to be a failure.

When the first charging voltage V_C1 is not the maximum chargingvoltage, the auxiliary power supply 100 may charge the charging circuit120 with the second charging voltage V_C2 in operation S35. At thistime, the level of the second charging voltage V_C2 may be higher thanthe level of the first charging voltage V_C1 by a first voltage amountDVC1.

Although an example, in which the auxiliary power supply 100 charges thecharging circuit 120 with the first charging voltage V_C1 or the secondcharging voltage V_C2, has been described with reference to FIG. 5,embodiments are not limited thereto.

After operation S30, the auxiliary power supply 100 may measure adischarge time, which is taken for the charging circuit 120 to bedischarged from the second charging voltage V_C2 to a second thresholdvoltage V_TH2. The auxiliary power supply 100 may determine whether thedischarge time is less than a second reference time interval TR2. Sincea voltage decrement of the charging circuit 120 (i.e., an absolute valueof a declining slope) increases over time, the second reference timeinterval TR2 may be shorter than the first reference time interval TR1in an example embodiment.

The level of the second threshold voltage V_TH2 may be lower than thelevel of the second charging voltage V_C2 by a second discharge voltageamount DV2. In an example embodiment, the magnitude of the firstdischarge voltage DV1 may be equal to the magnitude of the seconddischarge voltage DV2. However, embodiments are not limited thereto, andthe magnitude of the first discharge voltage DV1 may be different fromthe magnitude of the second discharge voltage DV2. For example, sincethe voltage decrement of the charging circuit 120 increases over time,the magnitude of the second discharge voltage DV2 may be set to behigher than the magnitude of the first discharge voltage DV1.

When a second discharge time, e.g., TD2, is shorter than the secondreference time interval TR2, the auxiliary power supply 100 maydetermine whether the second charging voltage V_C2 is the maximumcharging voltage.

When the second charging voltage V_C2 is the maximum charging voltage,the auxiliary power supply 100 may determine the charging circuit 120 tobe a failure. The auxiliary power supply 100 may inform outside theelectronic device 10, for example, a host, of the failure of thecharging circuit 120.

When the second charging voltage V_C2 is not the maximum chargingvoltage, the auxiliary power supply 100 may charge the charging circuit120 with a third charging voltage V_C3.

At this time, the level of the third charging voltage V_C3 may be higherthan the level of the second charging voltage V_C2 by a second voltageamount DVC2. In an example embodiment, the magnitude of the firstvoltage DVC1 may be equal to the magnitude of the second voltage DVC2.However, embodiments are not limited thereto, and the magnitude of thefirst voltage DVC1 may be different from the magnitude of the secondvoltage DVC2.

In an example embodiment, the auxiliary power supply 100 may controlcharge and discharge of the charging circuit 120 such that the voltageof the charging circuit 120 has a value between the third chargingvoltage V_C3 and a third threshold voltage V_TH3. The level of the thirdthreshold voltage V_TH3 may be lower than the level of the thirdcharging voltage V_C3 by a third discharge voltage DV3. In an exampleembodiment, the magnitude of the second discharge voltage DV2 may beequal to the magnitude of the third discharge voltage DV3. However,embodiments are not limited thereto, and the magnitude of the seconddischarge voltage DV2 may be different from the magnitude of the thirddischarge voltage DV3. For example, since the voltage decrement of thecharging circuit 120 increases over time, the magnitude of the thirddischarge voltage DV3 may be set to be greater than the magnitude of thesecond discharge voltage DV2.

The auxiliary power supply 100 may prevent electric energy stored in thecharging circuit 120 from decreasing due to the degradation of acapacitor by increasing a charging voltage of the charging circuit 120in stages as capacitance of the charging circuit 120 graduallydecreases.

FIG. 7 is a diagram for explaining the charging voltage information IVCstored in the auxiliary power supply 100, according to an exampleembodiment.

Referring to FIGS. 6 and 7, the charging voltage information IVC, i.e.,information about the charging voltage V_C with respect to the change incapacitance of a charging circuit, may be stored in the auxiliary powersupply 100. In an example embodiment, the charging voltage informationIVC may include information about the charging voltage V_C, a thresholdvoltage V_TH, and a reference time TR.

In a first period P1, the auxiliary power supply 100 may repeatedlyperform an operation of charging the charging circuit up to the firstcharging voltage V_C1 and an operation of discharging the chargingcircuit down to the first threshold voltage V_TH1 based on the chargingvoltage information IVC. When the first discharge time taken for thecharging circuit to be discharged from the first charging voltage V_C1to the first threshold voltage V_TH1 is shorter than the first referencetime interval TR1, the auxiliary power supply 100 may charge thecharging circuit with the second charging voltage V_C2. In an exampleembodiment, when the first discharge time is shorter than the secondreference time interval TR2, the auxiliary power supply 100 may skip astage of charging the charging circuit with the second charging voltageV_C2 and immediately charge the charging circuit with the third chargingvoltage V_C3.

In a second period P2, the auxiliary power supply 100 may repeatedlyperform an operation of charging the charging circuit up to the secondcharging voltage V_C2 and an operation of discharging the chargingcircuit down to the second threshold voltage V_TH2 based on the chargingvoltage information IVC. When the second discharge time taken for thecharging circuit to be discharged from the second charging voltage V_C2to the second threshold voltage V_TH2 is shorter than the secondreference time interval TR2, the auxiliary power supply 100 may chargethe charging circuit up to the third charging voltage V_C3.

In a third period P3, the auxiliary power supply 100 may repeatedlyperform an operation of charging the charging circuit up to the thirdcharging voltage V_C3 and an operation of discharging the chargingcircuit down to the third threshold voltage V_TH3 based on the chargingvoltage information IVC. When a third discharge time taken for thecharging circuit to be discharged from the third charging voltage V_C3to the third threshold voltage V_TH3 is shorter than a third referencetime interval TR3, the auxiliary power supply 100 may determine thecharging circuit to be a failure. The electronic device 10 may not usethe auxiliary power supply 100 based on information of failure. Althoughan example in which the third charging voltage V_C3 is the maximumcharging voltage has been described for convenience's sake, embodimentsare not limited thereto. In the case where the charging voltageinformation IVC further includes information about a fourth chargingvoltage having a higher level than the third charging voltage V_C3, theauxiliary power supply 100 may charge the charging circuit up to thefourth charging voltage when the third discharge time taken for thecharging circuit to be discharged from the third charging voltage V_C3to the third threshold voltage V_TH3 is shorter than the third referencetime interval TR3.

In an example embodiment, the level may gradually increase from thefirst charging voltage V_C1 to the third charging voltage V_C3. Thelevel may gradually increase from the first threshold voltage V_TH1 tothe third threshold voltage V_TH3. In addition, the length may graduallydecrease from the first reference time interval TR1 to the thirdreference time interval TR3.

In the drawings, the charging voltage information IVC includes the firstthrough third charging voltages V_C1 through V_C3 respectively havingdifferent levels, the first through third threshold voltages V_TH1through V_TH3 respectively corresponding to the first through thirdcharging voltages V_C1 through V_C3 and respectively having differentlevels, and the first through third reference time intervals TR1 throughTR3 respectively corresponding to the first through third chargingvoltages V_C1 through V_C3. However, this is just for convenience ofdescription, and the number of charging voltages respectively havingdifferent levels, the number of threshold voltages respectively havingdifferent levels, and the number of reference times respectively havingdifferent lengths in the charging voltage information IVC may be two orat least four.

FIG. 8 is a flowchart of the monitoring operation of the auxiliary powersupply 100 of the electronic device 10, according to an exampleembodiment. Redundant descriptions of like numerals in FIGS. 2, 5, and 8will be omitted. In an example embodiment, the monitoring operation ofFIG. 8 may be performed on the charging circuit 120 by the auxiliarypower supply 100 when external power is normally supplied to theelectronic device 10.

Referring to FIGS. 1, 6, and 8, when a discharge time, e.g., TD1, isshorter than the first reference time interval TR1 in operation S23, theauxiliary power supply 100 may perform operation S30 a. Operation S30 amay include operations S31 a, S33 a, and S35 a.

The auxiliary power supply 100 may determine whether the second chargingvoltage V_C2 is higher than the upper limit voltage V_L in operation S31a. The auxiliary power supply 100 may calculate the second chargingvoltage V_C2 by adding the first voltage amount DVC1 having apredetermined value to the first charging voltage V_C1, and then comparethe second charging voltage V_C2 with the upper limit voltage V_L. Theupper limit voltage V_L may have a level that allows the chargingcircuit 120 to normally operate and may have a predetermined value. Whenthe charging circuit 120 is overcharged exceeding the upper limitvoltage V_L, a normal operation of the charging circuit 120 may not beguaranteed.

When the second charging voltage V_C2 is higher than the upper limitvoltage V_L, the auxiliary power supply 100 may determine the chargingcircuit 120 to be a failure in operation S33 a. The auxiliary powersupply 100 may inform outside the electronic device 10, for example, ahost, of the failure of the charging circuit 120.

When the second charging voltage V_C2 is equal to or lower than theupper limit voltage V_L, the auxiliary power supply 100 may charge thecharging circuit 120 with the second charging voltage V_C2, which has alevel higher than the level of the first charging voltage V_C1 by thefirst voltage amount DVC1, in operation S35 a.

In an example embodiment, the first charging voltage V_C1 may be thecharging voltage V_C with which the charging circuit 120 is initiallycharged, and the first voltage DVC1 may have a predetermined value.

Although an example, in which the auxiliary power supply 100 charges thecharging circuit 120 with the first charging voltage V_C1 or the secondcharging voltage V_C2, has been described with reference to FIG. 8,embodiments are not limited thereto.

After operation S30 a, the auxiliary power supply 100 may measure adischarge time, which is taken for the charging circuit 120 to bedischarged from the second charging voltage V_C2 to the second thresholdvoltage V_TH2. When a second discharge time, e.g., TD2, is shorter thanthe second reference time interval TR2, the auxiliary power supply 100may determine whether the third charging voltage V_C3 is equal to orhigher than the upper limit voltage V_L. The auxiliary power supply 100may calculate the third charging voltage V_C3 by adding the secondvoltage amount DVC2 having a predetermined value to the second chargingvoltage V_C2, and then compare the third charging voltage V_C3 with theupper limit voltage V_L.

When the voltage of the third charging voltage V_C3 is equal to orhigher than the upper limit voltage V_L, the auxiliary power supply 100may determine the charging circuit 120 to be a failure. The auxiliarypower supply 100 may inform outside the electronic device 10, forexample, a host, of the failure of the charging circuit 120.

When the third charging voltage V_C3 is equal to or lower than the upperlimit voltage V_L, the auxiliary power supply 100 may charge thecharging circuit 120 with a third charging voltage V_C3.

In an example embodiment, the magnitude of the first voltage DVC1 may beequal to the magnitude of the second voltage DVC2. In other words, thesecond charging voltage V_C2 may increase to the third charging voltageV_C3 by the same level width as the first charging voltage V_C1increases to the second charging voltage V_C2. However, embodiments arenot limited thereto, and the magnitude of the first voltage DVC1 may bedifferent from the magnitude of the second voltage DVC2.

FIG. 9 is a diagram for explaining charging voltage information IVC′stored in the auxiliary power supply 100, according to an exampleembodiment.

Referring to FIGS. 6 and 9, the charging voltage information IVC′, i.e.,information about the charging voltage V_C with respect to the change incapacitance of a charging circuit, may be stored in the auxiliary powersupply 100. In an example embodiment, the charging voltage informationIVC′ may include information about an initial charging voltage, acharging voltage increment, the threshold voltage V_TH, and thereference time TR.

In the first period P1, the auxiliary power supply 100 may repeatedlyperform an operation of charging the charging circuit up to the initialcharging voltage, i.e., the first charging voltage V_C1, and anoperation of discharging the charging circuit down to the firstthreshold voltage V_TH1 based on the charging voltage information IVC′.When the first discharge time taken for the charging circuit to bedischarged from the first charging voltage V_C1 to the first thresholdvoltage V_TH1 is shorter than the first reference time interval TR1, theauxiliary power supply 100 may charge the charging circuit up to thesecond charging voltage V_C2 that is higher than the first chargingvoltage V_C1 by the first voltage amount DVC1.

In the second period P2, the auxiliary power supply 100 may repeatedlyperform an operation of charging the charging circuit up to the secondcharging voltage V_C2 and an operation of discharging the chargingcircuit down to the second threshold voltage V_TH2 based on the chargingvoltage information IVC′. When the second discharge time taken for thecharging circuit to be discharged from the second charging voltage V_C2to the second threshold voltage V_TH2 is shorter than the secondreference time interval TR2, the auxiliary power supply 100 may chargethe charging circuit up to the third charging voltage V_C3 that ishigher than the first charging voltage V_C1 by the first voltage amountDVC1 and the second voltage amount DVC2.

Although it is illustrated that the first voltage DVC1 and the secondvoltage DVC2 respectively having two different values are included inthe charging voltage information IVC′, embodiments are not limitedthereto, and the charging voltage increment may be set to a singlevalue. For example, the second charging voltage V_C2 may be higher thanthe first charging voltage V_C1 by the first voltage amount DVC1 and thethird charging voltage V_C3 may be higher than the first chargingvoltage V_C1 by twice the first voltage amount DVC1.

FIG. 10 is a block diagram of an electronic device 10 a according to anexample embodiment. Redundant descriptions of like numerals in FIGS. 1and 10 will be omitted.

Referring to FIG. 10, the electronic device 10 a may include anauxiliary power supply (or, an auxiliary power supply circuit) 100 a anda main system 200 a. The auxiliary power supply 100 a may supply anauxiliary power (or, an auxiliary voltage) to the main system 200 a andthe main system 200 a may operate using the auxiliary power. Thedescriptions of the main system 200 of FIG. 4 may be applied to the mainsystem 200 a.

In an example embodiment, the electronic device 10 a may include astorage device. For example, the electronic device 10 a may include anSSD.

The auxiliary power supply 100 a may include an auxiliary powermonitoring circuit 110 a and the charging circuit 120. The auxiliarypower monitoring circuit 110 a may store electric energy in the chargingcircuit 120 using external power and measure a voltage of the chargingcircuit 120.

The auxiliary power monitoring circuit 110 a may charge electric energyin the charging circuit 120 using an external power (or, an externalvoltage) while the external power is being normally supplied to theauxiliary power supply 100 a. The auxiliary power monitoring circuit 110a may enable the external power to be output to the second power linePL2 as a main power (or, a main voltage) and block the auxiliary powercharged in the charging circuit 120 from being output to the secondpower line PL2. When the external power is not normally supplied to theauxiliary power supply 100 a, the auxiliary power monitoring circuit 110a may block the main power from being output to the second power linePL2 and enable the auxiliary power in the charging circuit 120 to beoutput to the second power line PL2.

The auxiliary power monitoring circuit 110 a may monitor the voltage ofthe charging circuit 120. In an example embodiment, the auxiliary powermonitoring circuit 110 a may measure the voltage VNd of the chargingcircuit 120 and transmit a capacitor voltage signal S_VNd correspondingto the voltage VNd of the charging circuit 120 to the main system 200 a.In an example embodiment, the auxiliary power monitoring circuit 110 amay measure a discharge time, which is taken for the voltage VNd of thecharging circuit 120 to decrease from the charging voltage V_C (e.g.,the first charging voltage V_C1) to a threshold voltage (e.g., the firstthreshold voltage V_TH1), and transmit information about the dischargetime to the main system 200 a.

The auxiliary power monitoring circuit 110 a may control the chargingvoltage V_C provided to the charging circuit 120 in response to acharging voltage change command CMD_VC. For example, the auxiliary powermonitoring circuit 110 a may primarily charge the charging circuit 120with the first charging voltage V_C1 and, when receiving the chargingvoltage change command CMD_VC, charge the charging circuit 120 with thesecond charging voltage V_C2. At this time, the level of the secondcharging voltage V_C2 may be higher than the level of the first chargingvoltage V_C1.

The main system 200 a may operate using power supplied through thesecond power line PL2. The main system 200 a may include hardware orsoftware, each for controlling the auxiliary power supply 100 a. Themain system 200 a may output the charging voltage change command CMD_VCto the auxiliary power supply 100 a based on charging voltageinformation IVCa and a change in capacitance of the charging circuit120.

In an example embodiment, the charging voltage information IVCa, i.e.,information about the charging voltage V_C with respect to the change incapacitance of the charging circuit 120, may be stored in the mainsystem 200 a (e.g., the controller 220 in FIG. 4). In an exampleembodiment, the descriptions of at least one selected from the chargingvoltage information IVC of FIG. 7 and the charging voltage informationIVC′ of FIG. 9 may be applied to the charging voltage information IVCa.

The main system 200 a may receive the capacitor voltage signal S_VNd andobtain information about the voltage change of the charging circuit 120.The main system 200 a may detect a change in capacitance of the chargingcircuit 120 using the voltage change of the charging circuit 120. Forexample, the main system 200 a may detect a change in capacitance of thecharging circuit 120 by detecting a change in a discharge time taken forthe voltage VNd of the charging circuit 120 to be discharged from thecharging voltage V_C to the threshold voltage. When the capacitance ofthe charging circuit 120 is less than a reference capacitance, the mainsystem 200 a may output the charging voltage change command CMD_VC tothe auxiliary power supply 100 a.

In an example embodiment, the main system 200 a may receive informationabout the discharge time, which is taken for the voltage VNd of thecharging circuit 120 to be discharged from the charging voltage V_C tothe threshold voltage, from the auxiliary power monitoring circuit 110a.

FIGS. 11A and 11B are block diagrams of auxiliary power supplies 100 aand 100 a′ of the electronic device 10 a, according to exampleembodiments. Redundant descriptions of like numerals in FIGS. 3, 11A,and 11B will be omitted.

Referring to FIG. 11A, the auxiliary power supply 100 a may include theauxiliary power monitoring circuit 110 a and the charging circuit 120.The auxiliary power monitoring circuit 110 a may include a voltagemonitoring circuit 111 a, the first DC-DC converter 113, the secondDC-DC converter 115, the first switching circuit 117, and the secondswitching circuit 119.

The voltage monitoring circuit 111 a may measure a change in the voltageVNd of the charging circuit 120. The voltage monitoring circuit 111 amay monitor the voltage VNd of the charging circuit 120. The voltagemonitoring circuit 111 a may transmit the capacitor voltage signal S_VNdcorresponding to the voltage VNd of the charging circuit 120 to acontroller of a main system. In an example embodiment, the voltagemonitoring circuit 111 a may measure a discharge time, which is takenfor the voltage VNd of the charging circuit 120 to decrease from thecharging voltage V_C (e.g., the first charging voltage V_C1) to athreshold voltage (e.g., the first threshold voltage V_TH1), andtransmit information about the discharge time to the controller of themain system.

The voltage monitoring circuit 111 a may control the first DC-DCconverter 113 in response to the charging voltage change command CMD_VC.For example, the voltage monitoring circuit 111 a may control the firstDC-DC converter 113 such that the charging circuit 120 is primarilycharged with the first charging voltage V_C1 and, when receiving thecharging voltage change command CMD_VC, may control the first DC-DCconverter 113 such that the charging circuit 120 is charged with thesecond charging voltage V_C2.

In an example embodiment, the capacitor voltage signal S_VNd, theinformation about the discharge time, and the charging voltage changecommand CMD_VC may be transmitted through a bus that transfers signalsbetween the auxiliary power supply 100 a and the controller of the mainsystem. For example, the bus may transfer signals in an inter-integratedcircuit (I2C) mode.

In an example embodiment, the first DC-DC converter 113 may convert theexternal power to the first charging voltage V_C1 and provide the firstcharging voltage V_C1 to the charging circuit 120. When the capacitanceC (i.e., equivalent capacitance) of the charging circuit 120 is lessthan the first reference capacitance, the first DC-DC converter 113 mayprovide the second charging voltage V_C2, of which the level is higherthan the level of the first charging voltage V_C1, to the chargingcircuit 120.

In an example embodiment, the auxiliary power monitoring circuit 110 amay be implemented by a single chip. For example, the auxiliary powermonitoring circuit 110 a may form a PLP IC.

Referring to FIG. 11B, the auxiliary power supply 100 a′ may include anauxiliary power monitoring circuit 110 a′ and the charging circuit 120.The auxiliary power monitoring circuit 110 a′ may include a voltagemonitoring circuit 111 a′, a first DC-DC converter 113′, the secondDC-DC converter 115, the first switching circuit 117, and the secondswitching circuit 119.

The voltage monitoring circuit 111 a′ may measure a change in thevoltage VNd of the charging circuit 120. The voltage monitoring circuit111 a′ may monitor the voltage VNd of the charging circuit 120. Thevoltage monitoring circuit 111 a′ may transmit the capacitor voltagesignal S_VNd corresponding to the voltage VNd of the charging circuit120 to a controller of a main system. In an example embodiment, thevoltage monitoring circuit 111 a′ may measure a discharge time, which istaken for the voltage VNd of the charging circuit 120 to decrease fromthe charging voltage V_C to a threshold voltage, and transmitinformation about the discharge time to the controller of the mainsystem.

The first DC-DC converter 113′ may control the charging voltage V_C tobe output in response to the charging voltage change command CMD_VC. Forexample, the first DC-DC converter 113′ may primarily output the firstcharging voltage V_C1 and, when receiving the charging voltage changecommand CMD_VC, may output the second charging voltage V_C2.

In an example embodiment, the auxiliary power monitoring circuit 110 a′may be implemented by a single chip. For example, the auxiliary powermonitoring circuit 110 a′ may form a PLP IC.

Referring to FIGS. 11A and 11B, the auxiliary power supplies 100 a and100 a′ may prevent electric energy stored in the charging circuit 120from decreasing by increasing the charging voltage V_C of the chargingcircuit 120 in stages as the capacitance C of the charging circuit 120gradually decreases.

FIG. 12 is a block diagram of an example of applying the electronicdevice 10 or 10′ to an SSD, according to an example embodiment.

Referring to FIG. 12, an SSD system 1000 may include a host 1100 and anSSD 1200. The SSD system 1000 may include at least one selected from theelectronic device 10 of FIG. 1 and the electronic device 10 a of FIG.10.

The SSD 1200 may transmit and receive signals to and from the host 1100through a signal connector 1211 and may receive power through a powerconnector 1221. The SSD 1200 may include a plurality of flash memories1201 through 120 m, an SSD controller 1210, and an auxiliary powersupply 1220. The flash memories 1201 through 120 m may be used asstorage media of the SSD 1200. The SSD 1200 may use a non-volatilememory device, such as PRAM, MRAM, resistive RAM (ReRAM), or FRAM,besides flash memory. The flash memories 1201 through 120 m may beconnected to the SSD controller 1210 through a plurality of channels Ch1through Chm, respectively. At least one flash memory may be connected toa single channel. Flash memories connected to one channel may beconnected to one data bus.

The SSD controller 1210 may transmit and receive signals SGL to and fromthe host 1100 through the signal connector 1211. The signals SGL mayinclude a command, an address, data, and so on. The SSD controller 1210may write data to or read data from a certain flash memory according toa command from the host 1100.

The auxiliary power supply 1220 may be connected to the host 1100through the power connector 1221. The auxiliary power supply 1220 mayreceive power PWR from the host 1100 and be charged with the power PWR.The auxiliary power supply 1220 may be arranged inside or outside theSSD 1200. For example, the auxiliary power supply 1220 may be arrangedin a main board and may supply auxiliary power to the SSD 1200. Theauxiliary power supply 1220 may include at least one selected from theauxiliary power supply 100 of FIG. 3, the auxiliary power supply 100 aof FIG. 11A, and the auxiliary power supply 100 a′ of FIG. 11B.

When the capacitance of a charging circuit included in the auxiliarypower supply 1220 gradually decreases, the SSD 1200 may increase themagnitude of voltage, with which the charging circuit is charged, instages to prevent electric energy stored in the charging circuit fromdecreasing. Accordingly, the auxiliary power supply 1220 reliablysupplies power to the SSD 1200, and therefore, the operationalefficiency of the SSD 1200 may be prevented from decreasing and datastored in the SSD 1200 may be safely retained.

While the inventive concept has been particularly shown and describedwith reference to embodiments thereof, it will be understood thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the following claims.

1. A method of providing an auxiliary power by an auxiliary powersupply, the method comprising: converting an external power to aplurality of charging voltages; charging a charging circuit with a firstcharging voltage of the plurality of charging voltages; monitoring avoltage of the charging circuit; when capacitance of the chargingcircuit is less than a first reference capacitance, charging thecharging circuit with a second charging voltage of the plurality ofcharging voltages, the second charging voltage higher than the firstcharging voltage by a first voltage amount; and providing an auxiliarypower to outside the auxiliary power supply, wherein the auxiliary poweris generated based on the voltage of the charging circuit.
 2. The methodof claim 1, wherein when a discharge time taken for the voltage of thecharging circuit to decrease from the first charging voltage to a firstthreshold voltage is shorter than a first reference time interval, thecharging of the charging circuit with the second charging voltage isperformed.
 3. The method of claim 2, further comprising: when adischarge time taken for the voltage of the charging circuit to decreasefrom the second charging voltage to a second threshold voltage isshorter than a second reference time interval, charging the chargingcircuit with a third charging voltage of the plurality of chargingvoltages, the third charging voltage higher than the second chargingvoltage by a second voltage amount.
 4. The method of claim 3, whereinthe second reference time interval is shorter than the first referencetime interval.
 5. (canceled)
 6. (canceled)
 7. The method of claim 1,wherein the charging of the charging circuit with the second chargingvoltage includes: determining the charging circuit to be a failure whenthe second charging voltage that is calculated by adding the firstvoltage amount to the first charging voltage is higher than an upperlimit voltage for which the charging circuit can be charged to result innormal operation of the auxiliary power supply; and charging thecharging circuit with the second charging voltage when the secondcharging voltage that is calculated by adding the first voltage amountto the first charging voltage is equal to or lower than the upper limitvoltage.
 8. An auxiliary power supply circuit comprising: an auxiliarypower monitoring circuit configured to provide an auxiliary power tooutside the auxiliary power monitoring circuit; and a charging circuitconnected to the auxiliary power monitoring circuit, wherein theauxiliary power monitoring circuit comprises: a converter configured toconvert an external power to a charging voltage and to provide thecharging voltage to the charging circuit; and a voltage monitoringcircuit configured to control the converter based on capacitance of thecharging circuit, wherein the auxiliary power supply circuit isconfigured such that the voltage monitoring circuit controls theconverter to provide: a first charging voltage to the charging circuitwhen the capacitance of the charging circuit is equal to or greater thana first reference capacitance, and a second charging voltage higher thanthe first charging voltage to the charging circuit when the capacitanceof the charging circuit is less than the first reference capacitance,and wherein the auxiliary power is generated based on the capacitance ofthe charging circuit.
 9. The auxiliary power supply circuit of claim 8,wherein the auxiliary power supply circuit is configured such that whena discharge time taken for a voltage of the charging circuit to decreasefrom the first charging voltage to a first threshold voltage is shorterthan a first reference time interval, the voltage monitoring circuitdetermines that the capacitance of the charging circuit is less than thefirst reference capacitance.
 10. The auxiliary power supply circuit ofclaim 9, wherein further configured such that: when a discharge timetaken for the voltage of the charging circuit to decrease from thesecond charging voltage to a second threshold voltage is equal to orlonger than a second reference time interval, the voltage monitoringcircuit controls the converter to provide the second charging voltage tothe charging circuit, and when the discharge time is shorter than thesecond reference time interval, the voltage monitoring circuit controlsthe converter to provide a third charging voltage greater than thesecond charging voltage to the charging circuit.
 11. The auxiliary powersupply circuit of claim 10, wherein the second reference time intervalis shorter than the first reference time interval.
 12. (canceled) 13.The auxiliary power supply circuit of claim 8, wherein the voltagemonitoring circuit is configured to store charging voltage informationabout a charging voltage with respect to a change in the capacitance ofthe charging circuit, and to control the converter based on the chargingvoltage information.
 14. The auxiliary power supply circuit of claim 13,wherein the charging voltage information includes a magnitude of each ofthe first charging voltage and the second charging voltage.
 15. Theauxiliary power supply circuit of claim 13, wherein the charging voltageinformation includes a magnitude of the first charging voltage and adifference between the first charging voltage and the second chargingvoltage.
 16. (canceled)
 17. The auxiliary power supply circuit of claim8, wherein the auxiliary power supply circuit is configured such thatwhile the converter is converting the external power to the chargingvoltage and is providing the charging voltage to the charging circuitthe switching circuit is in an on state.
 18. A storage devicecomprising: an auxiliary power supply including a charging circuit andconfigured to receive an external power and to generate a main power andan auxiliary power based on the external power; and a main systemconfigured to control an operation of the auxiliary power supply,wherein the auxiliary power supply is further configured to charge thecharging circuit with a first charging voltage, and wherein the storagedevice is configured such that when capacitance of the charging circuitis less than a first reference capacitance, the auxiliary power supplycharges the charging circuit with a second charging voltage higher thanthe first charging voltage.
 19. The storage device of claim 18, whereinthe storage device is configured such that when a discharge time takenfor a voltage of the charging circuit to decrease from the firstcharging voltage to a first threshold voltage is shorter than a firstreference time interval, the auxiliary power supply determines that thecapacitance of the charging circuit is less than the first referencecapacitance.
 20. (canceled)
 21. The storage device of claim 18, whereinthe auxiliary power supply is configured to store charging voltageinformation about the first and second charging voltages with respect toa change in the capacitance of the charging circuit, and to determine amagnitude of the first and second charging voltages based on thecharging voltage information.
 22. The storage device of claim 18,wherein the main system is configured to store charging voltageinformation about the first and second charging voltages with respect toa change in the capacitance of the charging circuit.
 23. The storagedevice of claim 22, wherein the auxiliary power supply is configured totransmit a capacitor voltage signal corresponding to a voltage of thecharging circuit to the main system, and wherein the main system isconfigured to output a charging voltage change command for changing amagnitude of the first and second charging voltages based on thecapacitor voltage signal and the charging voltage information.
 24. Thestorage device of claim 23, wherein the auxiliary power supply furtherincludes a converter configured to convert the external power to thefirst and second charging voltages and to provide one of the first andsecond charging voltages to the charging circuit, and wherein theconverter is configured to convert a charging voltage from the firstcharging voltage into the second charging voltage in response to thecharging voltage change command.
 25. The storage device of claim 23,wherein the auxiliary power supply further includes: a converterconfigured to convert the external power to the first and secondcharging voltages and to provide one of the first and second chargingvoltages to the charging circuit; and a voltage monitoring circuitconfigured to monitor the voltage of the charging circuit and to controlthe converter, wherein the voltage monitoring circuit is configured tocontrol the converter to convert a charging voltage from the firstcharging voltage into the second charging voltage in response to thecharging voltage change command.